XTOL patented?

[gainer]

This is exactly why Kodak went with the TEA.SO2 adduct and patented it. It allows very great concentration of ingredients.

PE

I have seen the DEA version in the list of HC-110 ingredients.

 

[Photo Engineer]

DEA is considered a contaminant in TEA, and is not entirely desired in developers due to its great solvent effect on silver halide.

PE

 

[Ian Grant]

DEA in HC110 is only there only as Dead Link Removed

Ian

 

[Photo Engineer]

I was taking my impressions from work we did and that is probably in Haist an A&T. DEA is considered a contaminant in commercial TEA. The reason is that it is a variable impurity in TEA which causes variable pH and variable solvent effects. If it can be controlled, I would guess it would be a good solvent and work well, but i remain on the fence about this as an effective method for us as we cannot control DEA/TEA mixtures except by analysis.

I have TEA samples that vary from solid at 20 deg C and slightly yellow in color to totally clear and liquid at the same temp. AAMOF, I have 1 KG of each type sitting side by side on my DR shelf right now. This is the normal limit in variability of commercial photo grade TEA. Kodak apparently analyzes their TEA for DEA content and then dilutes it with DEA to obtain a constant value. In spite of the differences in my 2 samples, I have seen little difference in activity in most formulas although one test I ran showed a considerable difference in pH with a certain developer recently posted on APUG. These were not tested beyond rough imaging and pH, so I can't comment on image quality.

PE

 

[gainer]

The 99% grade of TEA, according to DOW, freezes at 15.8 C, (60.4 F) while the Commercial grade freezes at 21.8 C. (70.9 F). The pH of the commercial grade is somewhat higher at any solution strength. As you said, the 1% impurity is probably mostly DEA. www.DOW.com is the place to go for complete stats for MEA, DEA and TEA. We can purchase TEA at www.chemistry.com.

 

[Photo Engineer]

Interestingly, the melting point of most organics goes down as impurities rise. This seems to be counter to the norm by going up with lower grade (higher impurity).

PE

 

[gainer]

BTW, the TEA at chemistrystore is 99%. I forgot to pay attention to the melting point of DEA. It may be that the behaviour of Commercial TEA is more like a mixture of two related organics than a mixture of two or more completely unrelated organics. I don't even know if that is a good theory, but I suspect you will.

 

[Photo Engineer]

Mixtures of any organics of any nature, related or not, depress melting point to some extent. In fact, this method is a classic method of determining purity. The melting point expressed in degrees depression, and the spread of the melting point in degrees is a rough indication of purity. That is why the melting point of organics is often specified. A pure compound has an abrupt, sharp melting point with a range of less than 2 degrees C in general. Impure compunds can be depressed up to 20 deg C and melt sluggishly over a 10 degree range.

In synthetic organic lab, we were graded on yield and purity. The purity was expressed in melting point and C/H/N analysis in mole %.

PE

 

[Kirk Keyes]

It may be that the behaviour of Commercial TEA is more like a mixture of two related organics than a mixture of two or more completely unrelated organics.

The melting points of TEA is 21.6C and DEA is 28C. So an impurity of DEA should raise the melting point.

I'd suggest there's water causing a melting point suppression effect on the TEA and not something caused by the DEA.

Note that there are Low melting point grades of 85% TEA (99% TEA mixed with water to contain 15% water) which has a freezing point of -5C.

 

[Kirk Keyes]

Impure compunds can be depressed up to 20 deg C and melt sluggishly over a 10 degree range.

You knew you were in trouble when your nice, white organic lab product started getting all oily looking and then turned black when it was still a ways away from the stated MP. Oh well, there went a weeks worth of lab time. :^(

 

[Photo Engineer]

Kirk;

If TEA is in the majority, the TEA mp should be the governing value and it should be depressed, but if DEA is in the majority, the DEA mp would be the governing value and it woulld be depressed. Therefore, this mixture is either very much in favor of DEA content or it is one of those unusual situations where the MP is governed by the minority, high melting component.

PE

 

[Photo Engineer]

You knew you were in trouble when your nice, white organic lab product started getting all oily looking and then turned black when it was still a ways away from the stated MP. Oh well, there went a weeks worth of lab time. :^(

Yeah, and I had a few "pop" on me in the MP tube! I hated making picrates!

PE

 

[sanking]

DEA is considered a contaminant in TEA, and is not entirely desired in developers due to its great solvent effect on silver halide.

PE

Is there a practical way to test for the amount of DEA in a given TEA solution?

Sandy King

 

[Kirk Keyes]

Umm, do you know anyone with a High Performance Liquid Chromatography (HPLC) machine laying around?

 

[Photo Engineer]

Sandy;

For us, not really. I would assume that clear, colorless and solid TEA at about 20 deg C is probably good. Patrick has certainly noted a supplier of good grades and better grades of TEA.

PE

 

[gainer]

Is there a practical way to test for the amount of DEA in a given TEA solution?

Sandy King

Do you mean solutions in water or samples of TEA as it comes? The pH difference between 99% and Commercial grades is about 0.5 over the range of TEA-water solutions. The lines are parallel on a log scale. I am of the opinion that the major difference between the two grades is a small amount of DEA. The pH curve for pure DEA on the same plot is parallel to the others.

I would send you the whole document, but at my piddling rate of transmission one or another of us might not be around. I am scheduled for cardiac catheterization on the 15th. It shouldn't take long to send just the pH and freezing point curves. I'll post them here.

 

[Lee L]

Umm, do you know anyone with a High Performance Liquid Chromatography (HPLC) machine laying around?

http://www.make-digital.com/make/vol14/?pg=137
http://www.creative-technology.net/MAKE.html

Lee

 

[gainer]

Here, I hope, are the specs I said I would send.

Notice that at 100% solutions, TEA has a higher freezing point than DEA. At about 50% the order is reversed. These are not mixtures

 

[Photo Engineer]

Ummm, Patrick, I hope you noticed that these plots were ternary mixtures of MEA, DEA and TEA and that they had little information that applied to this discussion.

PE

 

[gainer]

Ummm, Patrick, I hope you noticed that these plots were ternary mixtures of MEA, DEA and TEA and that they had little information that applied to this discussion.

PE

Not so. Look again. They are comparison plots of the characteristics of the three different ethanolamines.
How could you get that from those curves? Can we have a ternary mixture with 50% of each of thee ingredients? What do you do with the 50% overflow? Worse yet, look at the right hand side, where we would have 100% of each of three ingredients.

 

[sanking]

Do you mean solutions in water or samples of TEA as it comes? The pH difference between 99% and Commercial grades is about 0.5 over the range of TEA-water solutions.

Pat,

I meant samples of TEA as it comes.

Sandy

 

[alanrockwood]

Umm, do you know anyone with a High Performance Liquid Chromatography (HPLC) machine laying around?

I have some in the group where I work, but unfortunately I would not be able to use them on a personal project.

Even better, I have mass spectrometers too, but again they would not be available for personal projects.

 

[alanrockwood]

The melting points of TEA is 21.6C and DEA is 28C. So an impurity of DEA should raise the melting point.

I'd suggest there's water causing a melting point suppression effect on the TEA and not something caused by the DEA.

Note that there are Low melting point grades of 85% TEA (99% TEA mixed with water to contain 15% water) which has a freezing point of -5C.

PE is right, impurities always depress the melting point. It is a general thermodynamic result... general as in the sense of "always", not in the sense of "usually".

This generalization applies to small amounts of impurities. However, in a two component system as the component of the "impurity" varies from a small percentage of the total toward being the main component then the roles of the two components reverse. The result is that there will be a minimum in the freezing point curve at some intermediate composition.

One last bit of trivia... it is the phenomenon of freezing point depression that is used as the basis of zone refining, a method to produce very pure compounds or elements.

 

[Photo Engineer]

Not so. Look again. They are comparison plots of the characteristics of the three different ethanolamines.
How could you get that from those curves? Can we have a ternary mixture with 50% of each of thee ingredients? What do you do with the 50% overflow? Worse yet, look at the right hand side, where we would have 100% of each of three ingredients.

Patrick;

The top graph is of binary, not ternary mixtures. I misread the graph and I apologize. This is a plot of the melting point of the 3 Ethanol amines as a function of water content.

The second plot is actually a pair and I missed the second plot. You need both to get pH vs concentration.

Although I was wrong, neither has a direct impact on our discussion. What we need is that data as a binary mixture of DEA/TEA in water at different concentrations and the MP and pH data. Silver halide solvent capacity would be good as well.

Alan;

Thanks for the clear explanation for the non chemists out there. Since we are generally faced with 95% TEA, then the DEA is a minor constituent and that is why I was surprised by the MP increase that Patrick reported above.

PE

 

[gainer]

Would water in the commercial TEA account for the fact that the pH of commercial TEA is higher than that of the 99%?
It is also true that the 99% TEA is readily capable of supercooling.
Dow at www.dow.com will surely have the answers to these questions if anyone is serious enough to try.

I am attaching the table of Typical Physical Properties from DOW.